/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.visitor;

import proguard.classfile.*;

/**
 * This <code>ClassVisitor</code> delegates its visits to one of two <code>ClassVisitor</code> instances, depending on
 * whether the name of the visited class file is present in a given <code>ClassPool</code> or not.
 *
 * @author Eric Lafortune
 */
public class ClassPresenceFilter implements ClassVisitor {
    private final ClassPool classPool;
    private final ClassVisitor presentClassVisitor;
    private final ClassVisitor missingClassVisitor;

    /**
     * Creates a new ClassPresenceFilter.
     * 
     * @param classPool the <code>ClassPool</code> in which the presence will be tested.
     * @param presentClassVisitor the <code>ClassVisitor</code> to which visits of present class files will be
     *        delegated.
     * @param missingClassVisitor the <code>ClassVisitor</code> to which visits of missing class files will be
     *        delegated.
     */
    public ClassPresenceFilter(ClassPool classPool, ClassVisitor presentClassVisitor,
        ClassVisitor missingClassVisitor) {
        this.classPool = classPool;
        this.presentClassVisitor = presentClassVisitor;
        this.missingClassVisitor = missingClassVisitor;
    }

    // Implementations for ClassVisitor.

    public void visitProgramClass(ProgramClass programClass) {
        ClassVisitor classFileVisitor = classFileVisitor(programClass);

        if (classFileVisitor != null) {
            classFileVisitor.visitProgramClass(programClass);
        }
    }

    public void visitLibraryClass(LibraryClass libraryClass) {
        ClassVisitor classFileVisitor = classFileVisitor(libraryClass);

        if (classFileVisitor != null) {
            classFileVisitor.visitLibraryClass(libraryClass);
        }
    }

    // Small utility methods.

    /**
     * Returns the appropriate <code>ClassVisitor</code>.
     */
    private ClassVisitor classFileVisitor(Clazz clazz) {
        return classPool.getClass(clazz.getName()) != null ? presentClassVisitor : missingClassVisitor;
    }
}
